1. Field of the Invention
This invention relates to an infusion bag and, more particularly, to an improved infusion bag that makes the infusible particles freely expand and improves the quantity and the speed of infusion of liquor flowing into and out of the infusion bag.
2. Description of the Prior Art
The prior art teaches various types of infusion bags, such as tea bags, for aiding the infusion of infusible particles. The infusible particles are packed in the lower end of the bags. After steeping, the infusible particles swell against one another and against packing sheets to form a compacted mass. The withdrawal and submerging of the bag causes the upper part of the packing sheets to adhere together, thereby permitting only limited quantities of infusion liquor to seep out of the bag. This is because the upper part of the bag is composed of substantially parallel sheets and also because of the interface capillarity of the compacted mass and the surface capillarity of the packing sheets. Furthermore, when the bag is withdrawn, only a limited quantity of liquor seeps out of the bag because no air can flow into the bag due to surface capillarity of the packing sheets. The atmospheric pressure forces the parallel packing sheets of the upper part of the bag to adhere together. The surface capillarity results from the liquor forming a thin film wetting the mesh of the packing sheets and the thin film makes the packing sheets air- and aroma-impermeable. Also, the surface capillarity of the packing sheets confines the aroma of infusion liquor in the hollow space of the bag. The interface capillarity of the compacted mass has the same effects and also forms bubbles between the particles of the infusible substance which limits the flow of the liquor into and out of the bag when the bag is withdrawn and submerged. Naturally, the smaller the quantity of infusion liquor seeping out of the bag, the smaller the quantity of infusion liquor which may reflow into the bag. Both surface capillarity and interface capillarity decrease infusion speed and lower infusion concentration.
In order to make infusion superior and to improve infusion speed, it is necessary to have a lower packing density, a larger packing space, and means for overcoming the surface capillarity of the packing sheets and the interface capillarity of the infusible compacted mass.
It is an object of this invention to provide a bag which overcomes the aforementioned inadequacies of the prior art bags and which allow an improved infusion of liquors.
Another object of this invention is to provide an improved infusion bag wherein the lower end of the bag is tapered to increase the infusion of liquor seeping out during withdrawal of the bag.
Another object of this invention is to provide an improved infusion bag wherein at least one ventilative slit is provided to overcome the surface capillarity of the packing sheets and the interface capillarity of the infusible compacted mass. Approximately fifty percent more in quantity of infusion liquor flowing into and out of the bag can be achieved. The slit is feasible only when the packing sheet is not parallel to the facing packing sheet. In this respect, the prior art bags can not be provided with a slit.
Another object is to provide an infusion bag of a three dimensional configuration which is easily folded into a flattened shape for easy packing in an envelope.
Another object is to provide an infusion bag wherein the packing sheets do not adhere together after steeping.
Another object is to provide an infusion bag wherein the internal volume to surface area ratio of the bag is larger than that of pillow-type, tetrahedral-type or tube-type bags.
Other objects will be apparent from the summary of the invention, the detailed description and the claims, taken in conjunction with the accompanying drawings.